In surgical operations of the abdomen, it is customary to employ a retraction apparatus to retain tissue away from the operative site. The retraction apparatus may include a frame or support ring rests over the patient surrounding the surgical opening and a number of retractors may be movably attached to the frame and flexibly positioned, with various clamping or positioning mechanisms, to reach into the surgical opening and retract surrounding tissue or organs.
By way of example, one system is disclosed in the various US patents, such as U.S. Pat. Nos. 4,254,763; 4,421,108; 4,424,724; 4,467,791; 5,520,608; 5,375,481; 6,241,659 and 6,530,883. In the so-called Bookwalter system, the frame element is a flat support ring with indentations. The support ring is held by a post that clamps to the side rail of the operating table and suspended in a plane above the surgical site. The retractor holder can engage with indentation on the support ring and allow retractor to slide into position.
Such a retractor holder is shown in U.S. Pat. Nos. 4,254,763; 4,421,108 and 4,467,791. The holder includes a spring-loaded pawl to lock the retractor handle in a fixed position and a slot to be slid on to the ring. The slot may incorporate a dowel or other pin with a smooth radius to matingly fit into an indentation on the support ring.
Another retractor holder shown in U.S. Pat. Nos. 4,424,724; 5,375,481; 6,241,459 and 6,530,883 includes a multi-position ratchet mechanism which permits a retractor blade to be rotated into the wound. The retractor holder with ratchet mechanism also has a slot with a dowel pin to engage one of the indentations on the outer circumferential edge of support ring. The engagement of indentation and the dowel pin provides a means for holding the position of retractor holder along the ring.
However, the engagement between the retractor holder, either with or without the multi-position ratchet mechanism, and the support ring is with only one dowel pin to engage with an indentation. Thus, the retractor holder may lose the engagement with the support ring when the holder rotates an angle. The rotation may cause the dowel pin to leave the indentation on the outer circumferential edge of support ring. When losing the engagement, the retractor holder may slide along the circumferential edge of ring. Indeed, the retractor holder with a dowel pin has a difficulty to rotate on the support ring.
To improve the rotation ability on the support ring, U.S. Pat. No. 6,241,659 further discloses the retractor stem has a round cross-section to rotate freely about it axis by an amount less than 45 degrees. However, rotating the retractor stem does not have the same effect as that of the retractor holder. Therefore, U.S. Pat. No. 6,620,097 tries to build a three-dimensional ratchet mechanism for retractor holder. However, the 3D retractor holder further needs a rotator indexing body and its mating member. It, somehow, complicates the structure, manufacture and assembly. Moreover, the 3D retractor holder utilizes a ball plunger to seat against the one of the indentations on the support ring. Since there is no locking device to secure the holder on the ring, the holder still has a difficulty to rotate on the support ring.
Because of the necessity of rotating the retractor holder on the support ring to hold tissue or organ in position, it is cumbersome to design a stopping device or lock device to secure the holder on the ring. It would be advantageous to have a mechanism in which the retractor holder can rotate and still hold on the support ring without slip. Thus, a retractor with such as a holder can rotate an angle on the support ring and hold the tissue in the wound.